import os

os.chdir(os.path.dirname(__file__))

fin = open('express.in')
s = fin.readline()
s = s.replace('\n', '')
fout = open('express.out', 'a')
fout.seek(0)
fout.truncate()
result = eval(s)  # 字符串表达式求值
result = '%.6f' % result
fout.write(str(result))
fin.close()
fout.close()
